A single acting compressed-air piston engine is already known and can also be designed to be double acting without much effort, wherein a working device is connected to each face of the compressed-air piston engine. The piston cylinder can thereby be constructed in one piece with the cylinder head or the cylinder bottom, however, it is advantageous when both the cylinder head and also the cylinder bottom are manufactured separately from the piston cylinder, and the parts are subsequently assembled, as this is, for example, done in Patent DE 33 42 388 C3 so that the necessary machining on the parts can be kept to a minimum.
The slide controls, which are needed for switching the linear movement of the working piston and are provided outside of the piston cylinder, are independent of this in such compressed-air piston engines and are placed so that the axes of the associated control piston of the control cylinder extend parallel to the axis of the working piston.
The slide control is either laterally attached to the piston cylinder and, if necessary, designed in one piece with same, or it is provided just like in the arrangement corresponding to DE 33 42 388 C3 above the cylinder head, or, if necessary, also below the cylinder bottom; the slide control can be structurally integrated into these structural parts. Both arrangements are unfavorable.
In the first case, it is not possible to change the working stroke of the working piston without having to exchange at the same time the entire slide control, which in each case is designed only for a specific working stroke and thus for a specific height of the piston cylinder. Since very different working strokes are needed for the various uses, the manufacturer of such a compressed-air piston engine must have many differently dimensioned slide controls in storage; an adapting of the working stroke by the user is not possible or only possible with great difficulties.
In the second case, the structural length of the compressed-air piston engine is significantly increased solely by the slide control because even if the control piston can be kept shorter than the working piston, it does require significant additional space in the axis extending direction of both pistons at the same time, which space is added to the required space for the working piston.
It is also already known to initiate the switching of the working piston through the initially-mentioned switch valves, in each case the valve piston rod moves a valve piston against the force of a return spring when it is carried along by the working piston in its working direction on the last portion of its working stroke; after the working stroke has been switched the return spring moves the valve piston including the valve piston rod again into its initial position.
The purpose of the invention is to overcome the above-described disadvantages of the known compressed-air piston engines of the type identified in detail above and to mount a slide control space-savingly and fittingly with respect to various working strokes of the working piston. Moreover, a further purpose of the invention is to design the needed mountings in such a compressed-air piston engine simply and to limit same to few structural parts.